1. Field of the Invention
This invention relates generally to an electronic still camera and, more particularly, to a power supply circuit for an electronic still camera having a flash generating device.
2. Description of the Background
In a so-called electronic camera, information relating to an image formed by the lens is converted into electrical signals and magnetically recorded on a magnetic record medium. In such camera, it is generally not required to supply power to both an image-producing portion and to a recording portion at the same time, for example, to a motor for driving a magnetic disc at the same time the focus of the lens is being adjusted. Therefore, there is usually an operating member provided to enable a first switch and a second switch to be closed in turn, so that when the first switch is closed by the operating member power is supplied to both the image-producing portion and the recording portion, whereby preparation for rotating the magnetic disc by the motor is made, the condenser used for generating flash is charged, and so on. Then, the second switch is closed, information of a desired image is magnetically recorded on the magnetic disc.
In the above-described electronic camera, however, when the first switch is closed, preparations for driving the motor and charging the condenser are simultaneously made, as represented in FIG. 5B. FIG. 5B graphically represents a time-current relation for the various operations, and shows that a concentrated charging current cannot be supplied to the main condenser for charging it in a relatively short period of time. Thus, the charging period for the condenser is unduly prolonged. Furthermore, a large charging current, for example, about 10A transiently flows for the duration of charging, particularly at the initial stage of charging, so that the voltage available for application to a signal processing circuit of the camera is reduced to an unacceptable level. Therefore, because of this voltage reduction, malfunctions of the signal processing circuit of the camera are apt to occur.